Undulator Hall Power Dissipation

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Undulator Hall Power Dissipation

• What is it and where does the heat go?

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Contents

• Air Flow
• Average heating
• Localized heating

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Air Flow

• From West to East only
• air is recirculated and brought back through a
  large duct in the Undulator Hall to the West end
• same direction as beam
• Constant flow rate 20,000 cfm
• Low average velocity, 1 mph

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Flow Characteristics

• Turbulent Flow --- Reynolds number for tunnel
  cross-section ( FH 21.5 ft) is 180,000.
• Low velocity --- 1 mph.

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Temperature Control

• Only one zone for temperature control
• just one temperature variable can be adjusted
• Temperature control
• Input temperature at discharge into the Undulator
  Hall will be held within 1 F at 68 F, with
  Process Heat Load up to 8.5 kW.
• The Process Heat Load is from the present and
  future undulator system equipment and doesnt
  include lighting or environmental heating/cooling
  sources.
• Note 8.5 kW is 50 W/m of tunnel and 65 W/m of
  undulator line

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Sources of Heating/Cooling

• Access
• People, equipment brought in, leakage of air
• Undulator System
• See next slide
• Tunnel walls and floor
• Initial warm up, seasonal variations, moisture
• Utilities
• Lighting, exit signs, power lines, chilled and
  hot water lines, phone/data/fire/pps
• Other systems
• DL2/Vertical Bend magnet wires
• Many different time scales quasi-static to random

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Undulator System Heating Loads

• F.O. Radiation Loss System
• Photodiode Radiation Loss System
• Camera Motors
• Cameras
• Quad magnets
• Corrector magnets
• Quad and Corrector Wires
• BPM RF Receivers
• BFM Sensor electronics
• HLS
• WPM
• Cable Drops

MPS Link Boxes Vacuum Pumps Magnet Water Lines
Convective load Quad Power Lines UCM Rack and
Contents Translation Motors CAM Motors Undulator
Motion IOC Diagnostic Motors Diagnostic Motor
IOC Photomultiplier
Current Estimate for Total Undulator System
Load 11 kW. . . (85 W/m of undulator line)
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Estimated Temperature Profile

• Total temperature rise of 1.0 deg C
• The temperature rise will increase with time as
  the tunnel warms up and additional heat loads are
  added.
• Probably want to offset discharge temperature 1 F
  to get mean at 68 F.

WEST
EAST
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Localized Heating

• Warm air from local heat sources will completely
  mix with tunnel air within a few (lt10) tunnel
  diameters
• Locally heated air persists in boundary layers
  which grow in size and mix with the main tunnel
  air stream.

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Forced Air Flow Around Racks or Pedestals

• Laminar layer forms around obstacle, eddies form
  downstream of it.
• ReD for support pedestals is about 30,000 so it
  will have same type of flow

From Kreith, pg 406
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Free Convection Air Flow Around Racks

• warmed air forms a thin boundary layer next to
  rack and rises
• air velocity at top of rack 2 ft per s

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Localized Heating Estimate

• 4-5 deg C air rises from the rack sides, more or
  less vertically, and warms a portion of the
  grider and segment
• Heat flows through the girder and segment and
  back into the air.

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Temperature averaging

• Effects of short term air temperature changes can
  be significantly averaged out.
• Example Undulator segment
• Measured response time constant ? 16 hrs. For
  temperature changes at period of 24 hr, ? 0.26
  hr-1, there is about a factor of 4 reduction in
  the response of the undulator temperature.

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Conclusions

• Tunnel air temperature will rise by 1 deg C or
  more along the tunnel length due to power
  dissipation
• Undulator system is the dominate heat source
• Localized heating was semi-quantitatively
  investigated
• 150 W racks placed under the segmentswill warm
  adjacent air 3-4 deg C
• Warmed air will rise and flow directly onto the
  girder and undulator segment